EP0551199A2 - Prüfgerät für elektrische Isolation und Durchgang - Google Patents

Prüfgerät für elektrische Isolation und Durchgang Download PDF

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Publication number
EP0551199A2
EP0551199A2 EP19930300102 EP93300102A EP0551199A2 EP 0551199 A2 EP0551199 A2 EP 0551199A2 EP 19930300102 EP19930300102 EP 19930300102 EP 93300102 A EP93300102 A EP 93300102A EP 0551199 A2 EP0551199 A2 EP 0551199A2
Authority
EP
European Patent Office
Prior art keywords
test
electrical
instrument according
electrical test
test instrument
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19930300102
Other languages
English (en)
French (fr)
Other versions
EP0551199A3 (en
Inventor
David Robert Harris
Martin Bernard Litherland
Arun Kumar Sehdev
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robin Electronics Ltd
Original Assignee
Robin Electronics Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robin Electronics Ltd filed Critical Robin Electronics Ltd
Publication of EP0551199A2 publication Critical patent/EP0551199A2/de
Publication of EP0551199A3 publication Critical patent/EP0551199A3/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/18—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for batteries; for accumulators
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/12—Circuits for multi-testers, i.e. multimeters, e.g. for measuring voltage, current, or impedance at will
    • G01R15/125—Circuits for multi-testers, i.e. multimeters, e.g. for measuring voltage, current, or impedance at will for digital multimeters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/28—Testing of electronic circuits, e.g. by signal tracer
    • G01R31/2832—Specific tests of electronic circuits not provided for elsewhere
    • G01R31/2836—Fault-finding or characterising
    • G01R31/2839—Fault-finding or characterising using signal generators, power supplies or circuit analysers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/54—Testing for continuity

Definitions

  • the present invention relates to an electrical test instrument, in particular an insulation and continuity tester, and more particularly to an instrument whose energy consumption is reduced, thereby increasing the life of its battery.
  • Typical insulation testers use a high voltage (often of the order of 1 kV) in order to stress any points that might be subject to breakdown and simultaneously draw a small test current (often of the order of 1 mA).
  • a known type of continuity tester has a switched power supply or regulator with a series resistor and develops several volts (typically 4 volts) across two test contacts when open circuit; the source voltage and series resistance are chosen such that several hundred mA (typically 300 mA) flow under short circuit conditions.
  • test button when a test button is pressed, a voltage is generated across a pair of test probes, the measuring system reads the voltage applied across the test probes and the current flowing through them and calculates the external resistance. The result of the test may then be indicated on a display.
  • the current drain on the battery is an important consideration.
  • insulation and continuity testers are concerned, although the current drain attributable to the measuring circuiting and display can be minimised by the use of low-power integrated circuitry and displays (eg LCD displays), the production of the test stimulus, whether it be the high voltage necessary for an insulation test or the current necessary to establish satisfactory continuity, by necessity involves a relatively heavy drain on the battery.
  • an insulation tester generating 1 kV at 1 mA or a continuity tester in closed circuit might take up to 1.0A from a 9V battery.
  • a problem of these testers is that a battery may be rapidly exhausted when making a series of tests and may only have a few hours life.
  • an electrical test instrument having circuitry for producing an electrical test signal.
  • the test instrument also has measurement means for making an electrical measurement with the test signal and control means for controlling energization of the circuitry.
  • the circuitry is controlled by the control means so that energization is interrupted once a measurement can usefully be obtained.
  • energization is interrupted once a steady measurement is obtained or alternatively when a measurement can be curve matched to a predetermined curve.
  • the present invention may be used in battery powered test instruments, i.e. those using a depletable energy store such as disposable or rechargeable batteries, so as to increase the amount of time which the tester can be used before the battery needs replacing or recharging.
  • a depletable energy store such as disposable or rechargeable batteries
  • control means controls the energization of the circuitry in accordance with the electrical measurements and to do this may analyze a series of measurements taken at a succession of sampling intervals.
  • control means may interrupt the energization of the circuitry after a predetermined time interval sufficient for a steady measurement to be obtained.
  • the electrical test instrument may test for continuity and/or insulation breakdown.
  • the present invention comprises a display, but equally, an audio generator such as a buzzer may alternatively or additionally be provided.
  • an audio generator such as a buzzer may alternatively or additionally be provided.
  • the electrical test instrument may have an additional mode of operation in which the control means may be prevented from interrupting the energization of the circuitry such that the electrical test signal is produced for as long as the switch is in the operating position.
  • FIG. 1 An insulation tester embodying the present invention is illustrated in Figure 1 and comprises a battery 2 supplying a high voltage generator 4 and a resistance measuring system 6 connected to test probes 8.
  • This tester is preferably portable and might be powered from, for instance, 6 AA 1.5V Alkaline cells or 1.5V R6 type batteries.
  • a high voltage (preferably of the order of 1 kV) may be used for testing in order to stress any points in the circuit under test that might be subject to breakdown.
  • the typical test current used in such a tester might preferably be 1 mA and a maximum may be up to 12mA.
  • An insulation tester of this type might preferably have three test ranges, namely 0-19.99 MOhm, 0-199.9 MOhm and 0-1999 MOhm.
  • the insulation test pressure is preferably chosen from 250 V, 500 V and 1000 V across a minimum of 250 kOhm, 500 kOhm and 1 MOhm respectively.
  • a microprocessor 20 operates an electronic switch 22 thereby causing a high voltage to be generated between the pair of test probes 8.
  • the measuring system 6 reads the voltage at the test probe terminals 8 and also the current flowing through them. It thereby calculates the external resistance and this resistance value is then indicated on the display 12 (which may be either analogue or digital and might preferably be LCD to reduce power consumption).
  • the continuity tester illustrated in Figure 2 comprises a switched power supply or regulator 14 with a series resistor 16 which presents several volts (preferably of the order of 4 volts) across the test probes when open circuit; the source voltage and series resistance being preferably chosen such that several hundred mA (typically 300 mA) flow under short circuit conditions, the relevant IEC standard calling for a minimum of 200mA to stress any weak points and to provide a good wetting current (hence a low resistance contact) in the circuit under test.
  • mA typically 300 mA
  • the measuring system 18 then calculates the external resistance from the voltage dropped by the known series resistor 16.
  • continuity tests may be made with the battery voltage when open circuit and limited by series resistor 16 under short circuit. Further, while the test button 10 is released, a resistance of a suitable value may be switched across the terminals to reduce effects of mains pick-up.
  • the tester is controlled by a microprocessor 20 using an analogue measuring circuit.
  • the microprocessor 20 switches on the power supply 4, by means of the electronic switch 22 and then monitors the voltage across the test probes 8. Once the rate of rise of this voltage is sufficiently small i.e. within a band in which the specified accuracy of the instrument can be achieved, the microprocessor 20 then switches off the power supply 4, 14.
  • Figure 5 shows the application of the invention in circumstances where the measured current is of interest, such as with an adaptation of the apparatus of Figures 1 and 2, in which a constant DC voltage is applied over an interval t o to t c , the resulting current waveform being due to the inductive nature of the load under test.
  • a series of voltage measurements are taken at a succession of sampling intervals until a stable voltage is reached.
  • the current flow (insulation test) or series voltage drop (continuity test) is then measured and the power supply 4, 14 may be turned off by means of the switch 22.
  • the results of the test for instance the resistance, is calculated and then shown on the display 12. The results may be held on the display until the test button 10 is released or, alternatively, they may be displayed for a predetermined time or until some other condition is met, for example when the test button 10 is next pressed.
  • the tester may produce a control signal for example to operate an audio alarm.
  • test signal subsequent to applying the test signal to the test probes 8, measurements may be taken until they can be matched to a predetermined curve such as that of a typical RC response curve and then the power supply to the test probes turned off.
  • the test signal may be turned off earlier than in the above embodiment since the rate of rise can still be relatively high when the test signal is turned off.
  • test signal to the test probes might automatically be switched off after a predetermined time.
  • the power source for the display 12 and measuring system 6,18 is not illustrated in the Figures, but may comprise a separate battery or power source or be the battery 2, connected directly and not through the switch 22.
  • microprocessor 20 may be connected to the display 12 and the measuring system 6, 18 to directly control them.
  • the tester may have a second mode, which we will call the TRAC mode.
  • the microprocessor 20 detects when the test button 10 is pressed, turns on the power supply 4, 14 by means of the electronic switch 22 and then determines when to turn off the power supply 4, 14. Hence, a single measurement is made and the test signals removed for each press of a test button.
  • the tester behaves in a manner similar to that of a conventional tester i.e. the voltage is applied at the test probes 8 as for long as the start button 10 is held down, readings being taken continuously.
  • the test signals are applied continuously and the displays are periodically updated while the button is held down.
  • the microprocessor 20 responding to the test button 10 in a different manner or alternatively, though not illustrated, another test button might bypass the electronic switch 22.
  • the two testers i.e. for insulation or continuity may be combined together in a single unit, with or without further test features such as those available with multitesters.
  • a switch may be provided to choose which test and hence which circuit is required.
  • the two or more circuits may share common components for example, the LCD display 12.
  • a further feature which can be included on the tester is a bar graph display and in the TRAC mode, the test voltage's magnitude may be displayed in real time on the bar graph, while a resistance reading is displayed visually.
  • a further embodiment is now described which uses a bar graph display in a novel function and also a numeric display.
  • the instrument will preferably provide a test current of typically 1.2 mA at minimum circuit load resistance, the minimum test current at maximum load will be 1 mA and the test pressure will fall as the current demand exceeds typically 1.2 mA.
  • the test button is up, external charge in the test circuit can be dumped through a resistor, the voltage between the test lead probes may be shown on the bar graph display and a right hand (RH) 0 may be shown on the numeric display.
  • the numeric display may clear to show an AC and a 'Lightning' warning symbol flashing in order to give an indication of dangerous voltages to the user.
  • a bleeper may be made to warble loudly and be distinct from an end-of-test signal which might be used. In this situation, the instrument will not respond to the test button in order to protect the instrument's circuits and also the user.
  • the bar graph can show the terminal voltage as it increases.
  • the numeric display may show a RH (Right Hand) 0.
  • the value may be shown on the numeric display with the M0hms unit and a bleeper may sound at a low level.
  • a measurement reading greater than the f.s.d of the selected range can be made to result in an over-range symbol being shown with the M0hms unit.
  • test voltage is applied continuously and the instrument may be such that every 2 seconds a fresh measurement is made, the numeric display is updated and the bleeper sounds at a low level. Meanwhile the test probe voltage may be measured every 100ms and the bar graph may be updated. The bar graph may also show circuit breakdown if it occurs.
  • test voltage is removed and the bar graph shows the terminal voltage as it decays.
  • the result shown on the numeric display clears to a RH 0 after 1 second (or alternatively 5 seconds) or immediately if the test button is pressed again to do another test.
  • the bar graph shows the increasing terminal voltage and a RH 0 is displayed.
  • the bar graph follows the charging voltage as it ramps up before making the measurement and as it then decays.
  • the measurement accuracy of the instrument will preferably meet the relevant standards: +-1.5% of reading +- 1 digit on continuity ranges +-1.5% of reading +- 1 digit on 20 M0hm, 200 M0hm +-3% of reading +- 1 digit on 2 G0hm range up to 1G0hm at 1kV. +-10% of reading +- 1 digit on 2 G0hm range up to 2 G0hm at 250V and 500V.
  • the voltage output accuracy for the insulation test will preferably meet the relevant standards: ⁇ 5% of nominal at minimum circuit load resistance.
  • the present invention offers substantial power saving because the test power supply 4, 14 is only switched on for the minimum time required to take a reading. It is ideally suited to battery powered testers since the time of major power consumption as illustrated in Figure 3 and 4 is kept to a minimum.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Measurement Of Resistance Or Impedance (AREA)
EP19930300102 1992-01-08 1993-01-07 Electrical insulation and continuity tester Withdrawn EP0551199A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9200273 1992-01-08
GB9200273A GB2264178A (en) 1992-01-08 1992-01-08 An insulation and/or continuity tester

Publications (2)

Publication Number Publication Date
EP0551199A2 true EP0551199A2 (de) 1993-07-14
EP0551199A3 EP0551199A3 (en) 1993-10-27

Family

ID=10708232

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19930300102 Withdrawn EP0551199A3 (en) 1992-01-08 1993-01-07 Electrical insulation and continuity tester

Country Status (2)

Country Link
EP (1) EP0551199A3 (de)
GB (1) GB2264178A (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2697092A1 (fr) * 1992-10-15 1994-04-22 Metrawatt Gmbh Gossen Multimètre numérique et procédé de mesure permettant l'exécution de mesures de résistance d'isolement.
WO1997020221A2 (de) * 1995-11-30 1997-06-05 Robert Bosch Gmbh Verfahren zur prüfung einer an einen niederfrequenzverstärker angeschlossenen impedanz und anordnung dazu
JP2000507798A (ja) * 1996-03-29 2000-06-20 ロビン エレクトロニクス リミテッド 電気設備をテストする方法および装置
AT11101U3 (de) * 2009-11-04 2011-01-15 Ditest Fahrzeugdiagnose Gmbh Multimeter
US11320462B2 (en) 2019-12-12 2022-05-03 Innova Electronics Corporation Electrical probe

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU1051876A (en) * 1975-02-19 1977-07-28 Ici Australia Ltd Current limiting means for battery
JPS61248028A (ja) * 1985-04-25 1986-11-05 Chinon Kk カメラ用閃光器の主コンデンサ充電方法および装置
DE3703908A1 (de) * 1987-02-09 1988-03-17 Bbc Brown Boveri & Cie Verfahren zur abschaltung einer stromquelle
DE4104371A1 (de) * 1991-02-08 1992-08-13 Siemens Ag Verfahren und schaltungsanordnung zur isolationspruefung von im untertagebergbau verlegten spannungsversorgungsleitungen

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1590946A (en) * 1976-08-17 1981-06-10 Bicc Ltd Cable testing apparatus
CA1132661A (en) * 1979-02-14 1982-09-28 Rodney Hayden Resistive device sensor
ATE21562T1 (de) * 1981-12-14 1986-09-15 Biddle Co James G Isolierungsanalysiergeraet und verfahren zur verwendung.
GB8513831D0 (en) * 1985-05-31 1985-07-03 Haines G J Testing cables
GB8807021D0 (en) * 1988-03-24 1988-04-27 Hanning Ltd Electrical test device
GB2239530B (en) * 1989-12-29 1993-07-21 Megger Instr Ltd Circuit checking

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU1051876A (en) * 1975-02-19 1977-07-28 Ici Australia Ltd Current limiting means for battery
JPS61248028A (ja) * 1985-04-25 1986-11-05 Chinon Kk カメラ用閃光器の主コンデンサ充電方法および装置
DE3703908A1 (de) * 1987-02-09 1988-03-17 Bbc Brown Boveri & Cie Verfahren zur abschaltung einer stromquelle
DE4104371A1 (de) * 1991-02-08 1992-08-13 Siemens Ag Verfahren und schaltungsanordnung zur isolationspruefung von im untertagebergbau verlegten spannungsversorgungsleitungen

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 11, no. 97 (P-560)26 March 1987 & JP-A-61 248 028 ( CHINON ) 5 November 1986 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2697092A1 (fr) * 1992-10-15 1994-04-22 Metrawatt Gmbh Gossen Multimètre numérique et procédé de mesure permettant l'exécution de mesures de résistance d'isolement.
WO1997020221A2 (de) * 1995-11-30 1997-06-05 Robert Bosch Gmbh Verfahren zur prüfung einer an einen niederfrequenzverstärker angeschlossenen impedanz und anordnung dazu
WO1997020221A3 (de) * 1995-11-30 1997-07-17 Bosch Gmbh Robert Verfahren zur prüfung einer an einen niederfrequenzverstärker angeschlossenen impedanz und anordnung dazu
JP2000507798A (ja) * 1996-03-29 2000-06-20 ロビン エレクトロニクス リミテッド 電気設備をテストする方法および装置
AT11101U3 (de) * 2009-11-04 2011-01-15 Ditest Fahrzeugdiagnose Gmbh Multimeter
US11320462B2 (en) 2019-12-12 2022-05-03 Innova Electronics Corporation Electrical probe

Also Published As

Publication number Publication date
GB2264178A (en) 1993-08-18
GB9200273D0 (en) 1992-02-26
EP0551199A3 (en) 1993-10-27

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